A conveyor belt is typically used to convey bulk material from one or more upstream loading points to a downstream discharge location. The material is normally dropped onto the moving belt at each loading point, either vertically or at an angle.
Skirting is used to contain the material while it settles down on the belt after loading. The skirting typically comprises upright barriers extending parallel to the longitudinal sides of the belt, a nominal distance in from the respective opposite edges. Each barrier is typically blade-like in shape, orientated in the direction of travel of the belt. Skirting need only be located in the vicinity of the each loading station and some distance downstream thereof.
Where there is more than one loading point on a conveyor, the material from an upstream loading point then has to enter back into a skirting arrangement at a downstream loading point. As material travels along on a conveyor it typically settles down and spreads out a bit, which means that even if material left the upstream loading station well contained with no material outside the skirting, by the time it gets to a downstream loading station there will often be a significant amount of material outside the alignment of the skirts.
There are two types of devices called ‘belt ploughs’, namely:
(i) belt ploughs located on the material carrying side of a conveyor belt and used to deflect or redirect the material being conveyed from one part of the belt to another, or off the belt altogether; and
(ii) belt ploughs located on the non material-carrying side (or return strand) of a conveyor belt to deflect or scrape off larger foreign objects that may get onto the belt, and could cause serious damage if they entered the nip point of a pulley.
This invention is directed to belt ploughs of the first type, and references herein to ‘belt ploughs’ are intended to refer to carrying side belt ploughs.
Moreover, the term ‘plough’ is intended to mean ‘plow’ in those countries where the latter spelling is used.
One type of belt plough is used to deflect or redirect outlying material on the conveyor belt back inside the alignment of the skirts, to avoid colliding with the skirts and spilling from the conveyor. It is important to make the distinction between the mode of operation of the blade-like skirting on the one hand and belt ploughs on the other. The skirting blades are not designed to deflect or redirect material that is already settled on the belt (as a plough does), but to contain it from spilling to unwanted (outer parts) of the belt.
If a belt plough does not remove or recover all the material from that part of the belt laterally outside the skirting, then it typically will lead to spillage/cleanup problems downstream.
It has been found that known belt ploughs do not perform this job properly and do not avoid spillage. With known belt ploughs in fixed arrangements, the plough blade quickly wears and allows material to pass through. In some arrangements, the whole plough assembly comprising the plough frame and blade(s) can “float” or pivot, but the applied bearing pressure or bias force on the belt surface then becomes excessive, along with the wear rate of the blades. The top surface of the belt often becomes exposed to excessive wear at the same time.
Consequently, it is quite common for the skirting to be extended all the way between the loading points to avoid this spillage problem, adding significantly to the cost of construction.
Most conveyor belts have vulcanised splices joining the separate sections from which the belt is made. However, there are also quite a large number of belts in service with mechanical clips joining the sections of belt, and these clips can protrude noticeably above the surface of the belt. In addition, the surface of the belt may be damaged for other reasons, leading to surface irregularities. Such raised belt joins and other surface irregularities can interfere with the operation of known plough blades.
It is an aim of the invention to provide an improved belt plough which overcomes or ameliorates one or more of the disadvantages or problems described above, or which at least provides the consumer with a useful choice.